change/upgrade solar pv system

[solargenerator]

I have a solar pv system whixh is 2 years old.

My setup is over two roofs east/south due to roof configuration.

3kw with aurora outd 3.6 using the twin mppt inputs. 13 x romag 235w. 9 x east, 4 x south with the 4 south paired up with to on the east to give give enough voltage for the twin mppt.

Installed before any type of power optimiser were readily available

Question is can i have my system altered with say the solaredge optimisers op (to use a solar edge inveretor) or opa (to keep my invertor) range without it affecting my FIT payments.
I am sure the optimisers will increase my yearly output due to he shading issues i have early morning, afternoon and the configuration of the panels to enable the use of the twin mppt.

Many thanks in advance. Andy.

 

[whinmoor]

Yes, I believe you can change inverters without it affecting the FiT side of things.

I'm not sure about the logic of switching to Solar Edge from a financial viewpoint. You'd need to remove all the panels to fix optimisers to the rails. If this needs scaffolding, you're looking at extra expense. You'd also need a Solar Edge inverter so that would need to replace your Power One. You're looking at close to £2k I reckon. The increase in output would be small in relation to the outlay.

 

[solargenerator]

Hi Whinmoor,

 

[whinmoor]

It depends, of course, on the extent of the shading. It might be worth considering if your current inverter fails.

 

[solargenerator]

my original sap was 2400, my actual 2 year average is 1815.

i have a major shading issue early morning and the 4 south panels are in the 2nd string with 2 east panels.
the power optimisers should negate alot of my problems and the upgrade cost could be lower than your suggested £2000 if i can configure to use my original auroa outd 3.6 invertor.

 

[whinmoor]

13 x 235w panels = 3055w.

We would have specified the 3.0 rather than 3.6 model if using Power One Aurora.

It sounds like your installer may have over-estimated the SAP calculation by under-estimating the extent of the shading.

Why not get the installer back and complain that your system is under-performing by 25%?

 

[solargenerator]

a spike in peak power has reached 3302w before, would this damage a outd 3.0?

your correct on the 3055w, was just rounding off.

 

[whinmoor]

According to the datasheet for these inverters, on the 3.0 the Max. Recommended DC Power [kW] = 3.5

(For the 3.6, you can go up to 4.15.)

Others have more experience with Power Ones so I'm sure they will give their views in due course. Especially as you're in the north, I'd prefer to undersize than oversize the inverter

 

[solargenerator]

Whinmoor thanks for your comments.

do you know what the max recommended is for only one of the mppt inputs to be used are?
quessing its half of the 4.15 you say the 3.6 can max input?

 

[Vegelen]

Whinmoor thanks for your comments.

do you know what the max recommended is for only one of the mppt inputs to be used are?
quessing its half of the 4.15 you say the 3.6 can max input?

PVI-3.0, PVI-3.6, PVI-4.2 | Power-One

Datasheet > United Kingdom > Download

 

[whinmoor]

Have a play with the Power One String Tool: Power-One Aurora Stringsizer?

You might pick something up which will come in handy when discussing it with your installer. Romag 235s are on there.

You can have unbalanced strings - you have to with 13 panels. But, 7+6 or 8+5 would be more logical than 9+4 from the inverter's point of view. It may be necessary to lower the activation voltage on the smaller string to ensure the inverter kicks into life at all. Did the installer do that?

 

[BruceB]

Max dc on one input of the 3.6kW inverter is 3kW.
You will find it on the UK data sheet in the downloads section of the Power One link in post #10

 

[whinmoor]

Reading the OP, did you say the 4 facing south are connected to some of the east panels? This will drag down the performance considerably.

 

[BruceB]

Power One also do optimisers now which might sort out problem panels.
I have not tried them yet.
Aurora Optimizer | Power-One

 

[whinmoor]

"with the 4 south paired up with to on the east to give give enough voltage for the twin mppt."

If "to" means "two", that seems like dodgy system design.
​

 

[solargenerator]

i have 7 + 6, the 6 is 4 south with 2 of the east.

smaller string is set to 120 startup.

no figuired that one myself after reading the manual and checking the invertor settings.

my generation outputs are on pvoutput. Andy1.
you can see from the summer graphs how the early morning sun is affected and then how ouput is lowering after midday.

 

[solargenerator]

reply #13.
yes the 4 south with the 2 east does greatly effect my output hence the "looking at solaredge optimisers"

- - - Updated - - -

reply #14.
power one optimisers £££££

 

[whinmoor]

Dodgy system design. The split orientations will drag each other down - that will be the main reason it's underperforming. I would recommend getting the installer back to redesign the whole lot. Probably need to get on roof and re-connect several of the panels. Get them to downsize the inverter at the same time.

 

[whinmoor]

I think you can do a 9+4 arrangement with the 3.0: Inverter utilization ratio:87.3%

With the 3.6 you have: Inverter utilization ratio:73.6%

 

[solargenerator]

great example of my early morning losses is 04/05/11 on pvoutput. Andy1

shows the early morning shading then the quick tail off of generation after midday.

 

[solargenerator]

would rather change the layout myself.
have scaffold tower, roof ladders and by now the knowledge.

 

[whinmoor]

would rather change the layout myself.
have scaffold tower, roof ladders and by now the knowledge.

Be careful! It's not really your job to rectify their error.

 

[solargenerator]

2 years since install

 

[Beavstro]

I would be seriously careful about changing an existing set up, I helped my company put a wind turbine through the MCS scheme ( which all products have to have in order to be eligible for FiT) and they were very clear that the product tested and its set up is what is eligible. For example your panels and the inverters (including how the inverters set up) must be the same as what was tested for the MCS certificate. Thus any change to the set up is not eliagble for the FIT as it is not what was tested.

Best option here is to talk to your installer of the product and see what options they have, as the panels MAY be able to be used with other parts without affecting eligibility of the FIT. As I'm sure you know, if you lose your FiT you will lose a lot of money!

 

[SolarCity]

Bad design. If the firm is still going then I'd give them a call and ask for their thoughts.

 

[solargenerator]

thanks for all your inputs.

power optimisers behind panels with original invertor sounds a good bet?

 

[Vegelen]

1) Your PVI-3.6-TL-OUTD Inverter is larger than it needs to be for your present setup.
2) If your Romag panels are Vmpp 30.6V per panel > 7 East facing = 214.2 V, 2 East + 4 South = 183.6V.
3) The voltages on each of your strings are operational but not optimum.
4) Putting 2 East with 4 South will reduce the amount you can generate on the 2nd string.
5) It would be benefitial to have 9 East facing panels connected to 1 string, but what would you do with the 4 south facing panels you've currently got, their voltage wouldnt be high enough for the 2nd string on a PVI-3.6-TL-OUTD ?
6) Aurora Optimisers may be benefitial, but at what price. What will you gain for your investment?
7) PVGIS indicates 9 East facing 235W panels in Durham (2.115 KWh) could generate 1400 KWh.
PVGIS Indicates 4 South facing panels 235W in Durham (0.94 KWh) could generate 784 KWh.
Thus 2184 KWh is the likely theoretical amount you'd expect to generate with a properly designed system.
8) Solar system design isn't always straightforward because of the roof types, spaces, orientations & inclinations installers have to work with.
9) Do I think the installer designed your system to its optimum, no?
10) How much could you gain by altering this system? 2184 KWh V 1815 KWh (17%)?
11) In reality solar optimisers are unlikely to generate what you'd expect because of the low combined south facing panel voltage, shading issues, greater efficiency losses etc.

If you had more roof space to install more south facing panels, you could seperate your East facing panels from your south onto individual strings with higher combined voltages that would improve things.
It may be best for you to accept what your generation is and be pragmatic about it.
Many people may generate more than you but how much of it do they productively use 33%?
How can you better utilise the energy you generate to exceed typical usage?

 

[solargenerator]

View attachment ConfigurationReport (3).pdfit may be possible to move one of the nine panels to the south orientation to give a 8 x 5, might be a squeeze but with a couple of joist hangers extra to support the panels at the foof edge.
with the 5 south panels on a voltage reduction of only 161v.

 

[Vegelen]

It is going to cost you more to change this system, than what you'll benefit from it.
Make better use of what you generate.

 

[solargenerator]

looking that way.

there maybe something around the corner.

will not stop looking for improvements.

 

[Worcester]

Using the power-one optimisers, looking at the datad sheet, you effectively configutre it all as one string, as each optimiser works as it's own mpp tracker.

If you do anything, that may be the most cost effective solution.

 

[Earthstore]

Why not change the 4 panels for Sunpower, or Panasonic, or was it jetson that are 50v?
Then if the inverter allows all the others could be wired on one string.
It may be more cost effective this way, without the potential of having to get back up on the roof every few years if you have any reliability issues.

It may need some careful system design, but then it should have had that in the first place.
Just a thought, that's all.

 

[Vegelen]

Why not change the 4 panels for Sunpower, or Panasonic, or was it jetson that are 50v?
Then if the inverter allows all the others could be wired on one string.

H J Solar are inexpensive, decent panels with a reasonable temperature coefficient:

H J Solar 250W HJM250M-32-BL or HJM250M-32 (Vmp 50.6, Voc 60.5):

http://reseller.segen.co.uk/reseller/docs/HJ Solar HJM250 255 260M - Datasheet Black Modules.pdf

Which solar panels were most affected by shading, was it the south or east or both?